Automated pipetting systems wherein small volumes from a number of reagents are pipetted into one or more cuvettes are known in the prior art. Applicants have made improvements in a number of components used in prior systems and have thus invented an improved apparatus for and an improved method of automatically pipetting reagents. Individual components thus improved are the aspirating pump, the device for picking up tips, the cap for bottles of reagents used in the procedure and the rack for holding those bottles. These improvements allow for an improved method of dispensing reagents which avoids cross-contamination of reagents and the cuvettes being loaded.